the zeatd being included in research conducted by 49er medical director dan garza and research assistant at stanford university. they showed me some head impact research from a different player during a game. they are pointing not necessarily where they are hit but where the acceleration. is pl n.f.l. is planning a ten-year study on the consequences of repeated head injuries. we want to have a way to understand how to measure the impacts that occur, not just from the concussions that you see happening, but from what we call the sub concussive events. >> cheryl: the doctor is chair of neurology department at ucsf and advisory committee to the n.f.l.. he is working with john york co-owner of the 49ers who was on the safety committee. they the tell me the n.f.l. is getting closer to find the best way to gather research on impacts to the brain, mouth guard sensors like this or helmets with sensors. >> i think we mayve the ability to put those into helmets or into mouth guards at the beginning of next season. >> it's such a weird injury. you are not sure. i think i'm okay. the brain sits in a